4MOST - 4-metre Multi-Object Spectroscopic Telescope

摘要

The 4MOST consortium is currently halfway through a Conceptual Design studyfor ESO with the aim to develop a wide-field (>3 square degree, goal >5 squaredegree), high-multiplex (>1500 fibres, goal 3000 fibres) spectroscopic surveyfacility for an ESO 4m-class telescope (VISTA). 4MOST will run permanently onthe telescope to perform a 5 year public survey yielding more than 20 millionspectra at resolution R~5000 ({\lambda}=390-1000 nm) and more than 2 millionspectra at R~20,000 (395-456.5 nm and 587-673 nm). The 4MOST design is especiallyintended to complement three key all-sky, space-based observatories of primeEuropean interest: Gaia, eROSITA and Euclid. Initial design and performanceestimates for the wide-field corrector concepts are presented. We consider twofibre positioner concepts, a well-known Phi-Theta system and a new R-Thetaconcept with a large patrol area. The spectrographs are fixed configurationtwo-arm spectrographs, with dedicated spectrographs for the high- andlow-resolution. A full facility simulator is being developed to guide trade-offdecisions regarding the optimal field-of-view, number of fibres needed, and therelative fraction of high-to-low resolution fibres. Mock catalogues withtemplate spectra from seven Design Reference Surveys are simulated to verifythe science requirements of 4MOST. The 4MOST consortium aims to deliver thefull 4MOST facility by the end of 2018 and start delivering high-level dataproducts for both consortium and ESO community targets a year later with yearlyincrements.